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Punctuation

Master punctuation rules for the SAT including commas, semicolons, colons, dashes, apostrophes, and end punctuation in various sentence structures.

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Punctuation

Commas

Required Uses

  1. Lists: "apples, oranges, and bananas"
  2. Introductory elements: "However, the results were surprising."
  3. Nonessential clauses: "My sister, who lives in Boston, is a doctor."
  4. Compound sentences with conjunction: "I ran, and she walked."
  5. Coordinate adjectives: "a tall, elegant building"

NOT Used

  • Between subject and verb: "The dog, ran away."
  • Before "that" in essential clauses: "The book that I read was great."
  • After a conjunction: "But, she disagreed."

Semicolons

  1. Join independent clauses: "I studied hard; the test was still difficult."
  2. Separate list items with internal commas: "cities including Paris, France; London, England; and Tokyo, Japan."

Key rule: Both sides of a semicolon must be complete sentences.

Colons

  1. Introduce a list, explanation, or elaboration: "She needed three things: food, water, and shelter."
  2. Must follow a complete sentence

Dashes

  • Em dash (—): Sets off nonessential information with emphasis. Can replace commas, colons, or parentheses.
  • "The results — which surprised everyone — were published yesterday."
  • Dashes come in pairs (like parentheses) unless at the end of a sentence.

Apostrophes

  • Possession: "the dog's bone" (singular), "the dogs' bones" (plural)
  • Contractions: "it's" = "it is" vs. "its" = possessive
  • Never for plurals: "apple's for sale"

SAT Tips

  1. If you can remove the phrase between commas/dashes and the sentence still works, the punctuation is correct
  2. Semicolons = period (both sides must be complete sentences)
  3. "Its" vs. "it's" is one of the most tested rules

📚 Practice Problems

1Problem 1easy

❓ Question:

Which is correct?

A) I like dogs, cats and birds. B) I like dogs, cats, and birds.

💡 Show Solution

Solution:

With 3 or more items, use commas to separate all items.

The comma before "and" is called the Oxford comma (SAT accepts it).

Answer: B - I like dogs, cats, and birds.

SAT Tip: In lists of 3+, use commas between all items!

2Problem 2medium

❓ Question:

Which is correct?

A) The movie was long, it lasted three hours. B) The movie was long; it lasted three hours.

💡 Show Solution

Solution:

Two independent clauses (complete sentences):

  • "The movie was long"
  • "It lasted three hours"

Cannot use comma alone → comma splice error!

Options:

  • Semicolon: "long**;** it lasted"
  • Period: "long**.** It lasted"
  • Comma + conjunction: "long**, and** it lasted"

Answer: B - The movie was long; it lasted three hours.

SAT Tip: Comma alone can't join two complete sentences!

3Problem 3hard

❓ Question:

Which is correct?

A) She had one goal: to become a doctor. B) She had: one goal, to become a doctor.

💡 Show Solution

Solution:

Colons introduce lists or explanations, but must follow a complete sentence.

A: "She had one goal" is complete → ✓ B: "She had" is incomplete → ✗

Answer: A - She had one goal: to become a doctor.

SAT Tip: Complete sentence before colon; fragment is okay after!

4Problem 4easy

❓ Question:

Which is correct? (A) "The experiment was successful, the results were conclusive." (B) "The experiment was successful; the results were conclusive."

💡 Show Solution

Answer: (B)

(A) is a comma splice — two independent clauses joined by only a comma. This is ALWAYS wrong.

(B) uses a semicolon to correctly join two related independent clauses.

Four ways to fix a comma splice:

  1. Semicolon: "...successful**;** the results..."
  2. Period: "...successful**.** The results..."
  3. Comma + conjunction: "...successful**, and** the results..."
  4. Subordination: "Because the experiment was successful, the results..."

Answer: (B) — the semicolon correctly joins two independent clauses.

SAT Rule: A semicolon works like a period — it connects two COMPLETE sentences that are closely related.

5Problem 5easy

❓ Question:

Which is correct? (A) "The experiment was successful, the results were conclusive." (B) "The experiment was successful; the results were conclusive."

💡 Show Solution

Answer: (B)

(A) is a comma splice — two independent clauses joined by only a comma. This is ALWAYS wrong.

(B) uses a semicolon to correctly join two related independent clauses.

Four ways to fix a comma splice:

  1. Semicolon: "...successful**;** the results..."
  2. Period: "...successful**.** The results..."
  3. Comma + conjunction: "...successful**, and** the results..."
  4. Subordination: "Because the experiment was successful, the results..."

Answer: (B) — the semicolon correctly joins two independent clauses.

SAT Rule: A semicolon works like a period — it connects two COMPLETE sentences that are closely related.

6Problem 6medium

❓ Question:

Add the correct punctuation: "The three primary colors red blue and yellow can be mixed to create secondary colors."

💡 Show Solution

The sentence needs commas to set off a list and an appositive:

"The three primary colors**—red,** blue**,** and yellow**—**can be mixed to create secondary colors."

Or with commas: "The three primary colors**,** red**,** blue**,** and yellow**,** can be mixed to create secondary colors."

Explanation:

  • "Red, blue, and yellow" is an appositive (renames "the three primary colors")
  • The appositive should be set off with dashes or commas
  • Within the list, use commas between items
  • Use the Oxford comma before "and" (standard for SAT)

Answer: "The three primary colors—red, blue, and yellow—can be mixed to create secondary colors."

SAT Note: The SAT uses the Oxford comma (comma before "and" in a list).

7Problem 7medium

❓ Question:

Add the correct punctuation: "The three primary colors red blue and yellow can be mixed to create secondary colors."

💡 Show Solution

The sentence needs commas to set off a list and an appositive:

"The three primary colors**—red,** blue**,** and yellow**—**can be mixed to create secondary colors."

Or with commas: "The three primary colors**,** red**,** blue**,** and yellow**,** can be mixed to create secondary colors."

Explanation:

  • "Red, blue, and yellow" is an appositive (renames "the three primary colors")
  • The appositive should be set off with dashes or commas
  • Within the list, use commas between items
  • Use the Oxford comma before "and" (standard for SAT)

Answer: "The three primary colors—red, blue, and yellow—can be mixed to create secondary colors."

SAT Note: The SAT uses the Oxford comma (comma before "and" in a list).

8Problem 8medium

❓ Question:

Which is correct? (A) "The CEO who founded the company in 2005 announced her resignation." (B) "The CEO, who founded the company in 2005, announced her resignation."

💡 Show Solution

It depends on context:

(A) No commas = restrictive clause → "who founded the company in 2005" identifies WHICH CEO (there must be multiple CEOs). The information is essential.

(B) With commas = nonrestrictive clause → "who founded the company in 2005" adds extra information about the ONLY CEO. The information could be removed.

On the SAT: If there is only ONE CEO (typical), the commas are correct because the clause is extra information.

Answer: Most likely (B) — the company typically has one CEO, so the clause is nonessential information.

Test: Try removing the clause. If the sentence still makes complete sense and identifies the right person, use commas (nonrestrictive). If you need the clause to know WHO is being discussed, no commas (restrictive).

9Problem 9medium

❓ Question:

Which is correct? (A) "The CEO who founded the company in 2005 announced her resignation." (B) "The CEO, who founded the company in 2005, announced her resignation."

💡 Show Solution

It depends on context:

(A) No commas = restrictive clause → "who founded the company in 2005" identifies WHICH CEO (there must be multiple CEOs). The information is essential.

(B) With commas = nonrestrictive clause → "who founded the company in 2005" adds extra information about the ONLY CEO. The information could be removed.

On the SAT: If there is only ONE CEO (typical), the commas are correct because the clause is extra information.

Answer: Most likely (B) — the company typically has one CEO, so the clause is nonessential information.

Test: Try removing the clause. If the sentence still makes complete sense and identifies the right person, use commas (nonrestrictive). If you need the clause to know WHO is being discussed, no commas (restrictive).

10Problem 10hard

❓ Question:

Choose the correct punctuation: (A) "The study found three things: lower costs, higher quality, and improved access." (B) "The study found three things, lower costs, higher quality, and improved access." (C) "The study found three things; lower costs, higher quality, and improved access."

💡 Show Solution

Answer: (A) — Use a COLON to introduce a list.

Why each option:

(A) Colon after "three things:" ✅

  • A colon introduces a list, explanation, or elaboration
  • What comes before the colon must be a complete sentence ("The study found three things" ✓)
  • What follows explains what those "three things" are

(B) Comma after "things," ❌

  • Creates a confusing run-on
  • The list items blur with the introductory phrase

(C) Semicolon after "things;" ❌

  • A semicolon requires a complete sentence on BOTH sides
  • "Lower costs, higher quality, and improved access" is not a complete sentence

Colon rules for SAT:

  1. What comes BEFORE the colon must be a complete sentence
  2. What comes AFTER can be a list, explanation, or another sentence
  3. Never use a colon after "such as," "including," or "for example"

11Problem 11hard

❓ Question:

Choose the correct punctuation: (A) "The study found three things: lower costs, higher quality, and improved access." (B) "The study found three things, lower costs, higher quality, and improved access." (C) "The study found three things; lower costs, higher quality, and improved access."

💡 Show Solution

Answer: (A) — Use a COLON to introduce a list.

Why each option:

(A) Colon after "three things:" ✅

  • A colon introduces a list, explanation, or elaboration
  • What comes before the colon must be a complete sentence ("The study found three things" ✓)
  • What follows explains what those "three things" are

(B) Comma after "things," ❌

  • Creates a confusing run-on
  • The list items blur with the introductory phrase

(C) Semicolon after "things;" ❌

  • A semicolon requires a complete sentence on BOTH sides
  • "Lower costs, higher quality, and improved access" is not a complete sentence

Colon rules for SAT:

  1. What comes BEFORE the colon must be a complete sentence
  2. What comes AFTER can be a list, explanation, or another sentence
  3. Never use a colon after "such as," "including," or "for example"

12Problem 12expert

❓ Question:

Fix all punctuation errors: "The author known for her vivid prose style, wrote three novels the last of which, won the Pulitzer Prize before she turned forty it was a remarkable achievement."

💡 Show Solution

Identify the issues:

  1. "The author known for her vivid prose style" — needs commas around the appositive
  2. "wrote three novels the last of which" — needs a comma or punctuation break
  3. "which, won" — unnecessary comma separating subject from verb
  4. "before she turned forty it was" — run-on / comma splice needs fixing

Corrected: "The author**,** known for her vivid prose style**,** wrote three novels**,** the last of which won the Pulitzer Prize before she turned forty**.** It was a remarkable achievement."

Or with a semicolon: "...before she turned forty**;** it was a remarkable achievement."

Or with a dash: "...before she turned forty**—**a remarkable achievement."

Changes made:

  1. Added commas around "known for her vivid prose style" (nonrestrictive)
  2. Added comma before "the last of which" (introduces a relative clause)
  3. Removed comma between "which" and "won" (don't separate subject and verb)
  4. Added period between "forty" and "It" (two independent clauses)

Answer: "The author, known for her vivid prose style, wrote three novels, the last of which won the Pulitzer Prize before she turned forty. It was a remarkable achievement."

13Problem 13expert

❓ Question:

Fix all punctuation errors: "The author known for her vivid prose style, wrote three novels the last of which, won the Pulitzer Prize before she turned forty it was a remarkable achievement."

💡 Show Solution

Identify the issues:

  1. "The author known for her vivid prose style" — needs commas around the appositive
  2. "wrote three novels the last of which" — needs a comma or punctuation break
  3. "which, won" — unnecessary comma separating subject from verb
  4. "before she turned forty it was" — run-on / comma splice needs fixing

Corrected: "The author**,** known for her vivid prose style**,** wrote three novels**,** the last of which won the Pulitzer Prize before she turned forty**.** It was a remarkable achievement."

Or with a semicolon: "...before she turned forty**;** it was a remarkable achievement."

Or with a dash: "...before she turned forty**—**a remarkable achievement."

Changes made:

  1. Added commas around "known for her vivid prose style" (nonrestrictive)
  2. Added comma before "the last of which" (introduces a relative clause)
  3. Removed comma between "which" and "won" (don't separate subject and verb)
  4. Added period between "forty" and "It" (two independent clauses)

Answer: "The author, known for her vivid prose style, wrote three novels, the last of which won the Pulitzer Prize before she turned forty. It was a remarkable achievement."

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Commas, Semicolons, and Colons
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❓ Frequently Asked Questions

What is Punctuation?▾
Master punctuation rules for the SAT including commas, semicolons, colons, dashes, apostrophes, and end punctuation in various sentence structures.
How can I study Punctuation effectively?▾
Start by reading the study notes and working through the examples on this page. Then use the flashcards to test your recall. Practice with the 13 problems provided, checking solutions as you go. Regular review and active practice are key to retention.
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Yes — all study notes, flashcards, and practice problems for Punctuation on Study Mondo are free to access. No account is needed.
What course covers Punctuation?▾
Punctuation is part of the SAT Prep course on Study Mondo, specifically in the Standard English Conventions section. You can explore the full course for more related topics and practice resources.
Are there practice problems for Punctuation?▾
Yes, this page includes 13 practice problems with detailed solutions. Each problem includes a step-by-step explanation to help you understand the approach.